Salmonella sp.,

about Salmonella sp.,

1. SALMONELLA SPECIES BY; K .Sanjay ,(BP211525), I M.Sc.Applied Microbiology, Sacred Heart College, Tirupattur . TO: Dr.P.Saranraj , Head of the Department, Department of Microbiology, Sacred Heart College, Tirupattur .

2. SYNOPSIS: General Characteristics Pathogenic species Pathogenicity V irulence factors Pathogenesis Clinical Diseases Laboratory diagnosis Colony morphology on Culture medium Biochemical Tests Serology Treatment and Prevention

3. General Characteristics: Gram Staining – Gram negative Shape – Rod Shape(Bacilli) Motility – Motile Capsule – Absent Endospore – Absent Respiration – Aerobic/Facultative anaerobic Optimum Temperature – 34°C to 37°C Optimum pH – 6.5 to 7.5 Habitat – Intestinal tract of humans and other animals The genus “ Salmonella ” was named after Daniel Elmer Salmon, a veterinary pathologist who ran a The United States Department of Agriculture (USDA) microorganism research program in the 1800s. Together with Theobald Smith, he found Salmonella in hogs that succumbed to the disease known as hog cholera.

4. PATHOGENIC SPECIES OF Salmonella sp Salmonella typhi Salmonella paratyphi Salmonella choleraesuis Salmonella typhimurium Salmonella enteritidis

5. PATHOGENICITY OF Salmonella sp. DISEASE TRANSMISSION Ingestion of contaminated food and water INCUBATION PERIOD 8 to 14 Days VIRULENCE FACTORS OF Salmonella sp . i . Endotoxin ii. Vi antigen (that increases virulence ) iii. Lipopolysaccharides iv . Invasion proteins v . Core polysaccharides vi . Somatic O antigen vii.Flagella H antigen

6. PATHOGENESIS OF Salmonella sp. After ingestion and passage through the stomach, Salmonella sp. attach to the mucosa of the Small intestine. bacteria remain in Endocytic vacuoles and replicate Bacteria transported across the Cytoplasm and released into the Blood Attachment, engulfment, and replication is controlled primarily by two large clusters of genes (pathogenicity island I and II) on the bacterial chromosome.

7. CLINICAL DISEASES CAUSED BY Salmonella sp . Gastroenteritis Gastroenteritis is the most common form Symptoms generally appear 6 to 48 hours after the consumption of contaminated food or water Fever , Abdominal cramps, Myalgia and Headache are also common Colonic involvement can be demonstrated Symptoms can persist from 2 to 7 days before spontaneous resolution. (ii) Bacteremia All Salmonella species can cause Bacteremia Risk For Salmonella bacteremia is higher in Pediatric and Immunocompromised patients Gram negative Bacteremia. However, Localized infections (e.g., Osteomyelitis, Endocarditis and Arthritis) can occur in as many as 10 % of patients .

8. (iii) Enteric fever or Typhoid fever A febrile illness called typhoid fever. A milder form of this disease, referred to as paratyphoid fever, is produced by salmonella paratyphi a Other salmonella serotypes can rarely produce a similar syndrome. Fever that starts low and increases daily, possibly reaching as high as 104.9 f (40.5 °c) (pyrexia) (iv) Asymptomatic colonization The strains of Salmonella responsible for causing Typhoid and Paratyphoid fevers are maintained by human colonization . Chronic colonization Chronic colonization with other species of Salmonella

9. LABORATORY DIAGNOSIS OF Salmonella sp . Microscopic examination Gram staining – Pink coloured Gram negative rods Motility test - Motile

10. Colony morphology on culture medium Nutrient agar - Colonies are circular, low convex, smooth, greyish white and translucent. Blood agar – Gamma Hemolysis MacConkey agar – Non - Lactose fermenting colonies Wilson – Blair Bismuth Sulfite agar – Jet black opaque colonies with metallic sheen . Xylose Lysine Deoxycholate (XLD) agar – Red translucent opaque colonies with black centre. Deoxycholate citrate agar (DCA) – Pale colonies. Salmonella – Shigella colonies (SSA) – Black colonies. Hektoen Enteric (HE) Agar – Transparent green colonies.

11. BIOCHEMICAL TESTS Catalase test - Positive Oxidase test – Negative Urease test – Negative Indole test – Positive Methyl Red (MR) test – Positive Voges Proskauer (VP) test – Negative Citrate utilization test – Positive SEROLOGY WIDAL Test (Widely Investigated Disease Assay Laboratory) Hydrogen Sulphide Test – Positive Ornithine Decarboxylase Test – Positive Triple Sugar Iron (TSI) Test – Alkaline slant, Acid butt, Gas produced and Hydrogen Sulphide produced.

12. TREATMENT AND PREVENTIVE MEASURES Antibiotic Therapy Infections with Salmonella typhi and Salmonella paratyphi or disseminated infections with other organisms should be treated with an effective antibiotics like a) Fluoroquinolones (e.g., Ciprofloxacin) b)Chloramphenicol c)Trimethoprim – Sulfamethoxazole d)Broad-spectrum Cephalosporin

13. Vaccination and Preventive measures Carriers of Salmonella typhi and Salmonella paratyphi should be identified and treated. Vaccination against Salmonella typhi can reduce the risk of disease for travelers into endemic areas. Most infections can be controlled by proper preparation of poultry and eggs (completely cooked) and avoidance of contamination of other foods with uncooked poultry products

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